Does running Redis in cluster mode on a single-node setup degrade performance or increases costs compared to a single-instance Redis?
From the docs
This means that in a Redis Cluster with N master nodes you can expect the same performance as a single Redis instance multiplied by N as the design scales linearly.
Can I use single-node redis cluster in production? The advantage of this is that you get horizontal scaling out-of-the-box.
What are the disadvantages?
All the stackoverflow answers I saw, recommend that we use single instance redis, but doesn’t really mention why.
2
Answers
Running Redis cluster mode on a single node isn’t ideal. While it prepares you for future scaling and mirrors production setups, it adds complexity, uses more resources, and doesn’t improve fault tolerance since all processes share the same failure point.
Single-instance Redis is simpler, faster, cheaper, and better suited for single-node setups unless you plan to scale out soon.
Advantage of cluster mode on a single-node:
Scalability: You get horizontal scaling out-of-the-box, making it easier to add nodes later.
Production-Like Setup: Useful for testing or staging environments that mirror a multi-node cluster.
Disadvantages of cluster mode on a single-node:
Complexity: Managing slots, cluster state, and debugging are more complicated than single-instance Redis.
Resource Overhead: Cluster mode runs multiple master processes, consuming more CPU and memory.
No Real Fault Tolerance: On a single node, all masters share the same failure domain, so there’s no added reliability.
Performance Impact: Cluster communication overhead adds latency without real benefits in single-node setups.
Higher Costs: Managed Redis services often charge more for cluster mode, with little ROI in this case.
As a resume for a single node, single-instance Redis is simpler, faster, and easier to manage. Cluster mode makes sense only if you’re planning to scale out soon or need logical sharding now. Otherwise single-instance Redis is ideal for better performance and efficiency.
It would probably increase performance since you have more endpoints you interact with, and the load is usually balanced between them.
It is a bit more safe, since a crash will wipe just a third of your data.
Not sure about cost, but if you have many changes in your topology in response to scaling etc. you’ll get some moved errors, and you will have extra calls.
It has extra overhead in managing, but if you use a good client library, you wouldn’t feel it, and you can also save costs using the latest valkey AZ affinity feature which supported by EC, and by valkey-glide client.